In various applications, for example a computed tomography application, an analog front end (AFE) is used to obtain digital data from analog data. The AFE includes a generating circuit. The generating circuit requires support circuitry. Often, the support circuitry consumes power, and area, produces high noise which in turn limits the performance of computed tomography application. Further, designing the support circuitry requires high cost. One such support circuitry is shown in FIG. 1 (Prior Art).
A dual integrator circuit for a generating circuit in an AFE as illustrated in FIG. 1 (Prior Art) provides digital data from an analog signal from the generating circuit. The dual integrator circuit requires lower area and less power consumption than other existing techniques. The dual integrator circuit provides a digitized charge value in response to a signal from the generating circuit when the generating circuit is struck by an X-ray beam. More particularly, the generating circuit, for example a photo detector 105, generates a current signal in response to the X-ray beam. The current signal is provided to an integrator circuit 110A when a switch 115A is active. The integrator circuit 110A generates an output voltage at a node 120A. The output voltage can be realized using a capacitor 125A. The output voltage is provided to a switched capacitor sigma delta (SCSD) modulator 130 to generate a digitized charge value. The digitized charge value represents a measured fraction of the X-ray beam. Similarly, an output voltage can be generated by an integrator circuit 110B when a switch 115B is active which can then be converted to a digital value. Noise introduced by each integrator circuit is given by the formula K*T*C, where C is capacitance of the capacitor 125A or 125B, K is a constant and T is temperature. It is also desired to support high current signal in order to get maximum digitized charge value. Maximum current signal that can be supported is given by (C*V)/t where, V is the output voltage, and t is time. The conditions for supporting low noise and maximum current signal are conflicting as for having low noise a low capacitance value is desired and for supporting high current signal a high capacitance value is desired. Further, it is also desired to minimize power burnt in each integrator circuit due to loads, for example a capacitor 125C and a capacitor 125D of the SCSD modulator 130.